Filter Press Operation

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Questions and Answers

What is the unit of the rate of washing in equation (9)?

m4/s

m/s

m2/s

m3/s (correct)

What is the effect of consolidation, channeling, and formation of cracks on the washing rate?

It decreases the washing rate (correct)

It has no effect on the washing rate

It is unpredictable

It increases the washing rate

What is the material used to manufacture the stationary and moving platen?

Stainless steel

Copper

Aluminum

Thick mild steel plates (correct)

Where is the inlet feed opening typically provided?

At the center or corner of the stationary platen Signup and view all the answers

What is the purpose of the hydraulic arm?

To open and close the filter press Signup and view all the answers

What is the function of the side bars?

To lock the stationary platen and headlock together Signup and view all the answers

What is the significance of the constant pressure in filtration and washing?

It allows for the same pressure to be used in filtration and washing Signup and view all the answers

What is the effect on the washing rate when the wash liquid travels through a cake twice as thick and an area only half as large in filtrating?

It reduces the washing rate to H of the final filtration rate Signup and view all the answers

What is the type of filtration described in the provided content?

Constant pressure filtration Signup and view all the answers

What are the only variables in the differential equation for constant pressure filtration?

V, t, and a Signup and view all the answers

What is the purpose of introducing compressed air in the filtration process?

To speed up the filtration process Signup and view all the answers

Why should the filter press be installed under shade?

To protect the filter plates from UV light damage Signup and view all the answers

What is the expression for KP in terms of mu, alpha, Cs, and deltaP?

KP = 2 * mu * alpha * Cs / deltaP Signup and view all the answers

What is the purpose of integrating the differential equation?

To obtain the filtration time Signup and view all the answers

What is the expression for t/V in terms of KP, B, and V?

t/V = KP * V + B Signup and view all the answers

What is the purpose of releasing the hydraulic pump?

To open up the press and discharge the cake Signup and view all the answers

What is the main assumption in the equation for the flow of filtrate through the packed bed of cake?

Laminar flow Signup and view all the answers

What can be calculated from the slope and intercept of the plot of t/V vs V?

KP and Rm Signup and view all the answers

What is assumed to be the same during washing as during filtration?

The conditions Signup and view all the answers

Why is the filtration process done at constant pressure?

It is the usual practice in batch process Signup and view all the answers

What is the purpose of shifting the filter plates?

To open up the press and discharge the cake Signup and view all the answers

What is the purpose of washing the filter cake?

To replace the slurry liquid with wash liquid Signup and view all the answers

What is the term for the equation that describes the filtration rate in batch processes?

Filtration equation for constant-pressure filtration Signup and view all the answers

What is the primary reason for calculating the area and thickness of cake?

To determine the volume of cake collected Signup and view all the answers

What is the purpose of drying a sample of the wet cake in the oven?

To calculate the percentage of water remaining in the wet cake Signup and view all the answers

What is the unit of filter-medium resistance?

m^-1 Signup and view all the answers

What is the purpose of evaluating the cake resistance and filter-medium resistance?

To optimize the filter press operation Signup and view all the answers

What is the primary purpose of the experiment?

To evaluate the efficiency of filter press Signup and view all the answers

What are the principles of cake filtration?

Not specified in the content Signup and view all the answers

What is the purpose of calculating the compressibility index of CaCO3?

To optimize the operation of the filter press Signup and view all the answers

What are the specific requirements that the septum in any filter must meet?

Not specified in the content Signup and view all the answers

What should be done to the filter cloths during the startup procedure?

They should be arranged properly and tied to prevent creases on the sealing face areas Signup and view all the answers

What is the purpose of checking the inlet feed pump maximum discharge pressure?

To prevent the filter press from exceeding its maximum feed pressure Signup and view all the answers

What is the hydraulic pressure setting formula for a filter press with a plate size of 470 x 470 mm and a ram size of 50 tons?

Ph = 32.7(Pf + 1) Signup and view all the answers

What is the minimum hydraulic pressure required for an Amston filter press size 630 with a 70 tons hydraulic ram, having a slurry feed pressure of 5 bars and a squeezing pressure of 7 bars?

327.2 kg/cm2 Signup and view all the answers

What is the purpose of operating the hydraulic hand pump during the closing of the filter press?

To extend the ram piston to push all the filter plates tight Signup and view all the answers

Why is it necessary to tighten the locking wheel (if applicable) during the closing of the filter press?

To secure the hydraulic ram in position Signup and view all the answers

What should be checked during the startup procedure of the filter press?

All filter plates, filter cloths, and filtrate outlet valves or spigots Signup and view all the answers

What happens if the inlet feed pump maximum discharge pressure exceeds the maximum feed pressure stated in the specification?

The filter press may be damaged Signup and view all the answers

Study Notes

Filtration Process

The filtration process involves introducing compressed air to inflate the membrane, speeding up the filtration process once the filtrate discharge is reduced.
The compressed air is released, and the hydraulic pump is opened, shifting the filter plates and discharging the cake.
The filter press should be installed in a shaded area to prevent direct sunlight, as the filter plates and cloths are made of polypropylene material sensitive to UV light.

Pressure Drop of Fluid Through Filter Cake

The flow of filtrate through the packed bed of cake can be described by an equation similar to Poiseuille's law, assuming laminar flow: ∆P = 2aµ / (LD)
Where a is a constant, ∆P is the pressure drop, L is the thickness of the cake, D is the filter cross-sectional area, and µ is the linear velocity.

Filtration Equation for Constant-Pressure Filtration

The basic equation for filtration rate in a batch process is:
- dv/dt = 2 KP / A (-∆P) V + B
Where KP is a constant, A is the filter cross-sectional area, ∆P is the pressure drop, V is the total filtration volume, and B is a constant.

Theory of Filtration

The filtration equation can be integrated to obtain the filtration time: t = (KP / 2) V^2 + BV
A plot of t/V vs V will be linear, with a slope equal to KP/2 and an intercept of B.

Washing of Filter Cakes and Total Cycle Time

The washing of a cake after the filtration cycle takes place by displacement of the filtrate and by diffusion.
The washing rate can be calculated using the equation: (dv/dt)f = 1 / (KF Vf + B)
Where (dv/dt)f is the rate of washing, KF is a constant, Vf is the final filtration volume, and B is a constant.

Experimental Equipment

The Amston filter press is designed to be simple and easy to operate, with a construction that allows for easy maintenance without disturbing the feed and filtrate piping.
The stationary and moving platen are manufactured from thick mild steel plates to provide a rigid and accurate closing of the filter press with minimal leakage.

Start-Up and Operating Procedures

The start-up procedures include checking the filter plate sequence, filter cloth arrangement, and filtrate outlet valves.
The operating procedures include closing the filter press, operating the hydraulic hand pump, and tightening the locking wheel to secure the hydraulic ram in position.

Results and Report

The experiment results include calculating the volume of cake collected, the weight of the wet cake, the percentage of water remaining in the wet cake, and the percentage of calcium carbonate recovery.
The experiment data is used to determine the parameters KP, B, a, and Rm, and to discuss the results.
The unit of filter-medium resistance is not specified.
The septum in any filter must meet specific requirements, including being able to withstand the operating pressure and having a smooth surface to prevent cake from building up.
The principles of cake filtration include the use of pressure difference to force the liquid through the filter cloth and cake, and the use of a filter medium to separate the solid and liquid phases.

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Description

Learn about the steps involved in operating a filter press, including inflation, filtration, and cake discharge. Understand the importance of installation and maintenance.